Electric ratchet wrench



Jan. 27, 1970 J. P. ALBERT ELECTRIC RATCHET WRENCH 2 Sheets-Sheet 1 Filed July 1, 1968 iwmrae .Am/m/ Awmr Jan. 27, 1970 J- PQALBERT ELECTRIC RATCHET WRENCH 2 Sheets-Sheet 2 Filed July 1, 1968 III/[ 110,1-

United States Patent 3,491,616 ELECTRIC RATCHET WRENCH Jean Paul Albert, 246 Connaught Ave., Moncton, New Brunswick, Canada Filed July 1, 1968, Ser. No. 741,740 Int. Cl. F16h N16 US. Cl. 74--625 Claims ABSTRACT OF THE DISCLOSURE An electric ratchet wrench having a socket head rotatable by an electric motor through a pair of intermeshing gear members driving a ratchet wheel into rotation. A pawl is pivotally mounted at one end to the casing of the ratchet wrench and a spring drives this pawl into engagement with the ratchet wheel whereby to allow manual turning of the ratchet head independently of the intermeshing gear members.

BACKGROUND OF THE INVENTION Field of the invention The present invention generally relates to an electrically actuated ratchet wrench of the type having a ratchet member adapted to. receive socket tools to tighten and loosen bolts, nuts and the like.

Description of the prior art Such electrically actuated ratchet wrenches are presently known but their disadvantage is that when the nut or bolt has been tightened to a predetermined extent and the motor is automatically uncoupled, manual handling of the wrench is possible to increase the tightening on the bolt or nut but only through the gear system responsible for the rotation of the nut or bolt thus often causing damage to the threads of the gear system.

SUMMARY OF THE INVENTION It is therefore a main object of the present invention to overcome this disadvantage by providing an electrically actuated ratchet wrench affording manual handling thereof, after rotation by the operating motor is terminated, but in which oscillation of the wrench to tighten the bolt or nut is carried out independently of the gear system.

More specifically, an object of the invention lies in the provision of an electric ratchet wrench having a gear drive for the rotation of a ratchet head and providing, in combination, a hollow casing adapted to serve as a wrench handle; an electric power means in the casing connected to the gear drive which comprises intermeshing gear members and at least one ratchet wheel driven by the said gear members; at least one pawl for manually rotating the ratchet wheel by oscillation of the casing, the said pawl being pivotally mounted at one end to the casing and resilient means being provided for biassing the pawl toward the ratchet wheel for operational engagement therewith whereby rotation of the ratchet wheel and bolt, nut or the like may be obtained manually independently of the intermeshing members.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and features of the invention will become evident from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, two embodiments in accordance with the present invention and, wherein:

FIGURE 1 is a perspective View of an electrically operated ratchet wrench according to the invention;

FIGURE 2 is a partial cross-sectional view of the wrench shown in FIGURE 1, and illustrating, in general,

Patented Jan. 27, 1970 ice DESCRIPTION OF THE PREFERRED EMBODIMENT Describing now the drawings in which like numerals are used to designate like parts and, turning attention initially to FIGURES 1, 2, 3 and 4, it will be seen that the device according to the invention is actuated by an electric motor 1, the housing of which is used as a handle. The motor 1 is powered by an external source (not shown) via a wire 2 and is operated by means of a motor activating switch, in the present instance the slide contact 3, known per se, and disposed on top of a handleextension 4 detachably connected to the motor housing.

Rotatable inside the handle extension 4, which also forms the casing for the device, is a shank 5 driven, at one end thereof by a motor shaft 6 via a slip-clutch 7 and, at its other end, formed with a worm 8 for driving a worm gear ring 9.

Freely rotatable inside the worm gear ring 9 is a ratchet wheel 10 provided with teeth at its rim and with a central orifice 11 to receive a socket member 12 (FIG. 1) for engaging the head of a bolt or nut, as usual. The ring 9 enclosing the ratchet wheel 10, is provided with pivotal pawls 13 and 14 pressed by the spring members 15 and 16 to ensure engagement of the pawls with the teeth.

The shank 5 driven by the motor 1, drives the ratchet wheel 10 via the worm and worm gear ring transmission and the drive pawls 13 and 14 arranged on the worm gear ring 9 in a manner known per se.

Should a nut or bolt being turned by the wrench be screwed up fast to the end of its travel, an excessive strain may result in the threads of the nut or bolt if the full power of the motor 1 has to be resisted by the threads at the moment they stop their rotary movement. In such an event, to prevent excessive strains on the bolt or nut threads and any part of the Wrench, an automatic power-decoupling device in the form of a slipclutch 7 is arranged between, and axially aligned with, the outer ends fo the motor shaft 6 and the shank 5.

As can be seen from FIGURES 2, 3 and 4, the slipclutch 7 consists of two tapered, cup-like friction elements 17 and 18, of well-known construction. The element 17 is fastened to the end portion 19, FIGURE 3, of the shank 5 by means of a key and key way arrangement 20 and the element 18 is connected to the shaft end portion 21, FIGURE 3, via a screw connection 22.

For operative driving engagement, the two elements 17 and 18 are frictionally coupled, i.e. the element 18 is axially fitted into the element 17.

To maintain driving engagement of the two elements 17 and 18, a tension spring 23 is provided to normally press the element 17 against the element 18.

The spring 23 surrounding the shank 5 is compressed between a stationary collar 24 and movable collar 25, parallel with each other and, each provided with central passages 24a and 25a, respectively, to permit longitudinal and rotational movement of the shank 5 passing therethrough.

Contrary to the stationary collar 24, the collar 25 is movable lengthwise along the shank 5 and transmits the spring pressure to the element 17 via a ball-bearing, ar-

rangement 26 disposed to prevent rotative movement of the spring 23 as well as the two collars 24 and 25.

Pressure of the spring 23 is adjustable by means of a plurality of pressure regulators 26a(one only being shown) connected to the collar 24 to radially displace same, FIG- URE 1, along the shank 5 to regulate the distance between the two collars so as to more or less compress the spring 23. For each regulator, a pin 26b is slidably displaceable in an inclined slot 26c through the wall of extension 4.

The spring 23 further functions to normally hold the worm 8 in position on the worm gear ring 9 and to prevent longitudinal movement thereof.

One side of the extension 4 is provided with a conically truncated bracket 27 integrally formed therewith and projecting endwise away therefrom and having a circular passage 28 arranged therein, coaxially with the shank 5.

The passage 28 is adapted to position the end portion 29 of the shank 5, e.g. via an adaptor 29a rotatable therewith and, adapted to prevent tilting movement thereof; the end portion 29 being arranged to rotatably journal in and through the passage 28.

Decoupling of the friction members 17 and 18, and subsequent disconnection of the electric drive, takes automatically place when the member, e.g. a nut, being tightened by the ratchet wheel 10 has reached the end of its travel and its resulting resistance to further rotation blocks the ratchet wheel 10 which, in turn, via the uni-directional drive pawls 13 and 14, halts rotary movement of the gear ring 9; due to its acquired torque, the worm 8 driven by the shank 5 is forced to journal on forwardly outwardly (see FIG. 4) over the blocked gear ring 9 with the result that the friction member 17 connected to the shank 5 is disconnected from the member 18 and further rotation of the shank 5 and worm 8 is prevented.

One of the main features of the invention is that it allows manual tightening of the bolt or nut being screwed, after disengagement of the clutch 7, without involving the meshing arrangement of the worm 8 and the worm gear ring 9 and consequently eliminating any possibility of damaging the threads thereof. This is obtained, in the instant invention, by an auxiliary drive pawl 30 pivoted, at one end, to a support plate 32 depending from the lower side of the casing 4 and biassed, by means of a spring 31, into teeth 32a of the ratchet member 10. Thus, for manual rotation, this auxiliary pawl 30 takes over from pawls 13 and 14 so that the torque is applied directly from the casing 4 to the ratchet wheel 10 without going through the worm coupling 8-10.

Upon release of the ratchet wrench from the nut or bolt being screwed, the shank 5 will be forced leftward by the spring 23, bringing clutch 7 into frictional engagement again.

It will also be understood that the resistive torque at which the frictional clutch 7 is disengaged may be adjusted by varying the strength of spring 23 by longitudinal displacement of the collar 24 through the pressure regulators 26a, as aforesaid.

Now, with reference to another embodiment of the invention illustrated in FIGURE 5, the motor 1 is first connected to an overrunning slip-clutch 40, of conventional design, adapted to automatically disengage the coupling elements thereof upon a torque of a predetermined magnitude being applied thereto as when the nut or bolt being screwed creates a predetermined resistance. Slip-clutch 40 is in turn connected to a reversible unidirectional pawl clutch 42 also of conventional design, such as that used on ratchet screwdrivers. The connection is through shaft 6. The output of clutch 42 is connected to a bevel pinion 44 through shank 5.

As is known, the reversible unidirectional pawl clutch 40 will allow driving of the pinion 44 in one direction only, the pinion being freely rotatable in the reversible direction. The driving direction may however be changed by moving the actuating lever 46 (axially of casing 4) of the said clutch 42 over to the other of the two available positions.

Pinion 44 meshes with a gear ring or crown 48, rotatably mounted in the handle extension 4. A ratchet wheel 50 is solidly mounted on one, side of the gear ring and is provided, circumferentially thereof, with pawl teeth 56. A boss 52 integral with and projecting from wheel 50 is formed with a square head 54 for the reception of a socket member.

Actuating lever 46 of clutch 42 is fixed to, or integral with, a collar 58 circumseribing clutch 42 and providing with a pair of radial cars '60. To these ears 60 are connected pawl levers 62, 62' slidably extending across a transverse wall 64 of the housing 4. Lever 62 is made to press on one arm of a bellcrank pawl 66 pivoted, at the fulcrum 68 thereof, to the housing 4,

Pawl-operating lever 62 has an out-turned end 70 bearing against a boss 72 of a straight lever 74 pivoted at 76- to the housing 4. Boss 72 is connected to the straight portion of pawl 74 by an inclined ram 78.

Pawls 66 and 74 are driven into alternate engagement with the ratchet wheel 50 by springs 80, 80' as will hereinafter be explained.

Collar 58, and consequently actuating lever 46 of reversible clutch 42, is displaced by an operating mechanism comprising a pair of T-shaped members 82 fixed at one end to collar 58 and pivoted at the other end to the prongs of a fork 84 pivoted at 85 and having a handle 86 the end of which is guided in limited vertical displacement by a pin 87 slidable in a slot 88 of a pusher 90 displaceable by means of a finger-slider 92 through a button 94 slidably displaceable in a longitudinal slot 96 across the wall of housing 4. A lever 98 is connected at one end to the handle 86 of fork 84 and to a switch 100 for reversing the direction of rotation of motor 1, It must be assumed that a separate switch is provided (now shown) for energizing motor 1.

The aforedescribed embodiment operates as follows:

Assume shaft 6 and pinion 44 rotate in clockwise direction through universal reversible pawl clutch 42 as shown by arrow a and cause counterclockwise rotation of gear ring 48 and ratchet wheels 50 as shown by arrow b. Assuming the member (nut or bolt) to be tightened has right-hand threads, ratchet wheels 50 and gear ring 56 will stop after a predetermined resistance has been met, causing disengagement of the overrunning slip-clutch 40. Should further tgihtening of the nut or bolt be necessary, the handle extension 4 is then rotated manually counterclockwise whereby to cause rotation of the ratchet wheels 50 through pawl 66 engaged in one of the teeth 56.

It may however happen that when the ratchet wheel 50 stops due to the aforesaid resistive torque, the pawls 66 do not sit at the bottom between two successive teeth 56 and a certain slack must be taken up so that at first there is a slight relative movement between the handle extension 4 and the ratchet wheel 50 as well as gear ring 48. This relative motion causes pinion 44 to rotate clockwise which is then permitted by the uni-directional reversal pawl clutch 42. Consequently, manually operation of the wrench will never cause any strain between the teeth of gear ring 48 and those of pinion 44.

From the above description and from FIGURE 5, it will easily be understood that rearward displacement of finger-slider 92 will cause reversal of the motor 1, disengagement of pawl 66 and engagement of pawl 74 with the ratchet wheel 50, allowing operation of the device in reverse direction.

It will also be understood that a speed-reducer should be provided between motor 1 and slip-clutches 7 of FIG- URES 1 through 4 and 40 of FIGURE 5.

I claim:

1. In an electric ratchet wrench having a gear drive for rotating a ratchet head to turn bolts, nuts or the like, the improvement in the combination comprising:

(a) a hollow casing adapted to serve as a wrenchhandle;

(b) an electric power means in said casing connected to said gear drive for actuation thereof;

(c) wherein said gear drive comprises intermeshing gear memers and at least one ratchet wheel driven by said gear members;

(d) at least one pawl for manually rotating said ratchet wheel by oscillation of said casing;

(e) means pivotally mounted said pawl at one end to said casing; and

(f) resilient means for bi-assing said pawl toward said ratchet wheel for operational engagement therewith whereby rotation of said ratchet wheel and bolt, nut or the like may be obtained manually independently of said intermeshing gear members.

2. A combination as claimed in claim 1, wherein said intermeshing gear members are a worm and a gear ring; said ratchet Wheel is rotatably mounted on and coaxial with said gear ring, and ratchet pawls are provided on said gear ring and are resiliently biassed in engagement with said ratchet wheel to cause rotation thereof when said gear ring is rotated by said worm and power means.

31 A combination as claimed in claim 2, wherein said power means comprises an overrunning slip-clutch having a shank at the output thereof on which said worm is mounted and bearing means on said casing in which the free end of said shank journals and so constructed to allow limited displacement of said shank and worm when said clutch uncouples as a result of said gear drive reaching a predetermined resistive torque and said worm slipping over said gear ring.

4. A combination as claimed in claim 1, wherein said overrunning clutch consists of tapered cup-like friction elements engageable with one another and wherein resilient means is provided to bias said friction elements into relative engagement, said shank being connected at one end to one of said friction elements.

5. A combination as claimed in claim 4, wherein said friction element resilient means is an adjustable spring compressed between a first and a second radial collar disposed along said shank; said first collar being stationary with respect to said casing and said second collar being arranged to transmit pressure from said spring to one of said friction elements.

6. A combintaion as claimed in claim 5, including means to adjust the position of said first collar with respect to said second collar to regulate the distance between said collars in order to more or less compress said spring.

7. A combination as claimed in claim 1, wherein said gear members are a pinion operatively connected to said power means and a crown; said ratchet wheel is coaxially fixed onto said crown to be driven thereby; said power means comprises a reversal uni-directional ratchet clutch operatively connected to said crown whereby said crown may alternately be driven in either clockwise or counterclockwise direction and be freely rotatable in the corresponding opposite direction; there are two pawls mounted for manual rotation of said ratchet wheels; said ratchet clutch having an actuating arm to cause reversal of rotation of said pinion and means, connected to said actuating arm, is provided to cause engagement of either one of said pawls with said ratchet wheel and disengagement of the other.

8. A combination as claimed in claim 7, wherein said actuating arm is movable lengthwise of said casing between a forward and a retracted position and said last named means comprises: a rigid element fixed to said actuating arm and extending transversely of said casing; a pair of pawl actuating levers fixed at the end of said rigid element to be displaced longitudinally of said casing between said forward and retracted positions; said pawls and pawl levers arranged so that one of said pawls moves to engagement with said ratchet wheel while the other moves away therefrom upon said rigid element and actuating arm moving from one of said positions to the other.

9. A combination as claimed in claim 8, wherein said last named means further includes an operating mechanism operable from outside said casing to move said actuating lever and rigid element between said two positions.

10. A combination as claimed in claim 9, wherein said power means includes an electric motor and an electric switch to cause reversal of rotation of said motor and means is provided between said switch and said operating mechanism to cause actuation of said switch and the reversal of said motor when said actuating lever and said rigid element moved from one of said positions to the other.

References Cited UNITED STATES PATENTS 2,420,552 5/ 1947 Morrill 74625 2,586,293 2/1952 Birkigt l9256 3,120,845 2/1964 Horner 74625 FRED C. MATTERN, 111., Primary Examiner W. S. RATLIFF, 1a., Assistant Examiner US. Cl. X.R. 

